There are live cameras at Seaton depot and Colyford station too. on youtube.

 

I believe that branch lines could be electrified at much lower cost than at present. New conductor rail installations are de facto banned.
A cheaper possibility would be OHLE at 750 volts DC. Already used for trams so the equipment is at least somewhat standard.
DC electric trains are a mature and well understood technology, and the train need not "know" that the current is from an overhead wire and not a live rail.
The move away from all 25 KV AC would be regrettable, but arguably a price worth paying for cheaper, simpler, and less obtrusive electrification of branch lines. Performance would be limited to keep down the current and the related costs, but remember we are talking of branch lines, not intercity.
A class 159 has reasonable performance with a power of about 900 kw,  something similar but electrically powered is probably about the sensible limit with 750 volt DC overhead.

 

I wonder if that was in any way to do with the anniversary?  A year later and it's been there 53 years!
https://en.wikipedia.org/wiki/Seaton_Tramway

 
110 volts DC is relatively low risk, touching it should be avoided for just in case, but is unlikely to be fatal.
110 volts could be used for full size trams or other vehicles but performance would be limited.
Fairgrounds used 110 volts DC and treated it very casually, accidents no doubt occurred but were infrequent.

 
I did look out for you yesterday Roger!

 
There can also be queues first thing at Colyton. Last Tuesday the first service left passengers behind despite a duplicate tram running. Queues at both ends that day. On duty at Wetlands Halt tomorrow so won't see the queues, except Seaton at lunchtime

 
Took a trip to the Seaton Tramway today and thoroughly enjoyed it.

We elected to start our journey from the Colyton end - attracted by the free parking there.  It seemed to be the right decision as we were travelling against the flow as it were with most visitors starting out from Seaton judging by the size of the queues as we arrived at Seaton on the first leg and back at Colyton when we returned.

Colyton is a delightful station with a small cafe and gift shop.   Two new stations have recently been opened on the three mile route which gives walkers better access to the wetlands which are next to part of the line through the Axe Valley.

For £12 you can buy a ticket to travel all day - which even if you only do one round trip represents good value for around 45 minutes of travelling.

 

The Seaton Tramway is a 2'9" gauge line with trams weight about 7 tons (I asked one of the team there because even Google couldn't help me) electrified at 110 volts and 3 miles long, top speed 17 mph

a National Rail line would be a different kettle or fish.  Lets try one

The line to xxxx would be a 4'8.75 gauge line with 3 car train weighing 115 tons electrified at 25,000 volts and 25 miles long, top speed (say) 60 m.p.h. to make it practical for regular passenger use

All sorts of scalability issues - not to lessen the achievements in Seaton

 

Not a direct answer to your question, but these articles may prove of interest:

http://www.tautonline.com/powering-trams-electrification-masterclass-part-one/

http://www.tautonline.com/powering-trams-part-two/

 
...my thoughts are - if a private individual/small group were able to introduce OHL on a shoestring (presumably) for this tramway why cannot Network Rail electrify branchlines at reasonable cost?

I am expecting a whole load of reasons from forum members more knowledgeable than I am.

 
The Ranty Highwayman's last holiday blog includes the Seaton Tramway
https://therantyhighwayman.blogspot.com/2021/09/five-go-mad-in-dorset-part-3-sunny.html
Maybe members of the forum could comment on a Highway Engineers view's, including